Giant cell arteritis is an inflammation of the lining of your arteries. Most often, it affects the arteries in your head, especially those in your temples. For this reason, giant cell arteritis is sometimes called temporal arteritis.

Giant cell arteritis frequently causes headaches, scalp tenderness, jaw pain and vision problems. If left untreated, it can lead to stroke or blindness.

Prompt treatment with corticosteroid medications usually relieves symptoms of giant cell arteritis and may prevent loss of vision. You'll likely begin to feel better within days of starting treatment. But even with treatment, relapses are common.

You'll need to visit your doctor regularly for checkups and treatment of any side effects from taking corticosteroids.

The most common symptoms of giant cell arteritis are head pain and tenderness — often severe — that usually affects both temples. The onset of the condition can feel like the flu.

Generally, signs and symptoms of giant cell arteritis include:

Persistent, severe head pain, usually in your temple area

Scalp tenderness

Jaw pain when you chew or open your mouth wide

Fever

Fatigue

Unintended weight loss

Vision loss or double vision, particularly in people who also have jaw pain

Sudden, permanent loss of vision in one eye

Pain and stiffness in the neck, shoulders or hips are common symptoms of a related disorder, polymyalgia rheumatica. About 50 percent of people with giant cell arteritis also have polymyalgia rheumatica.

When to see a doctor

If you develop a new, persistent headache or any of the problems listed above, see your doctor without delay. If you're diagnosed with giant cell arteritis, starting treatment as soon as possible can usually help prevent vision loss.

Almost any large or medium-sized artery can be affected, but swelling most often occurs in the arteries located in the temples. These are located just in front of your ears and continue up into your scalp. Sometimes the swelling affects just part of an artery with sections of normal vessel in between.

Just what causes these arteries to become inflamed isn't known. Certain genes and gene variations may increase your susceptibility to the condition.

Blindness. Diminished blood flow to your eyes can cause sudden, painless vision loss in one or, rarely, both eyes. Loss of vision is usually permanent.

Aortic aneurysm. An aneurysm is a bulge that forms in a weakened blood vessel, usually in the aorta, the large artery that runs down the center of your chest and abdomen. An aortic aneurysm may burst, causing life-threatening internal bleeding. Because this complication may occur even years after the initial diagnosis of giant cell arteritis, your doctor may monitor the health of your aorta with annual chest X-rays or other imaging tests, such as ultrasound and CT.

Stroke. This is an uncommon complication of giant cell arteritis.

You may start by seeing your primary care doctor. He or she may refer you to an eye specialist (ophthalmologist) if you're having visual symptoms, a brain and nervous system specialist (neurologist) if you're having headaches, or a specialist in diseases of the joints, bones and muscles (rheumatologist).

You may want to take a friend or family member with you to the appointment. Sometimes it can be difficult to remember all the information provided. Having someone with you may help you remember something that you missed or forgot.

Here's some information to help you get ready for your appointment.

What you can do

Before your appointment make a list of:

Any pre-appointment restrictions. At the time you make the appointment, be sure to ask if there's anything you need to do in advance. For some tests involved in diagnosing giant cell arteritis, you may need to follow special instructions before the appointment.

Symptoms you've been having, including those that seem unrelated to the reason for which you scheduled the appointment.

Key personal information, including any major stresses or recent life changes.

What you can do in the meantime

Giant cell arteritis can be difficult to diagnose because its early symptoms resemble those of many common conditions. For this reason, your doctor will try to rule out other possible causes of your problem.

To help diagnose giant cell arteritis, you may have some or all of the following tests and procedures:

Physical exam. In addition to asking about your symptoms and medical history, your doctor is likely to perform a thorough physical exam, paying particular attention to your temporal arteries. Often, one or both of these arteries are tender with a reduced pulse and a hard, cord-like feel and appearance.

Blood tests. If your doctor thinks you might have giant cell arteritis, you're likely to have a blood test that checks your erythrocyte sedimentation rate — commonly referred to as the sed rate. This test measures how quickly red blood cells fall to the bottom of a tube of blood. Red cells that drop rapidly may indicate inflammation in your body.

You may also have a test that measures C-reactive protein (CRP), a substance your liver produces when inflammation is present. The same tests may be used to follow your progress during treatment.

Biopsy. The best way to confirm a diagnosis of giant cell arteritis is by taking a small sample (biopsy) of the temporal artery. The procedure is performed on an outpatient basis during local anesthesia, usually with little discomfort or scarring. The sample is examined under a microscope in a laboratory.

If you have giant cell arteritis, the artery will often show inflammation that includes abnormally large cells, called giant cells, which give the disease its name. It's possible to have giant cell arteritis and still have a negative biopsy result. If the results aren't clear, your doctor may advise another temporal artery biopsy on the other side of your head.

Imaging tests may be used for diagnosing giant cell arteritis and for monitoring your response to treatment. Possible tests include:

Magnetic resonance angiography (MRA). This test combines the use of magnetic resonance imaging (MRI) with the use of a contrast material that produces detailed images of your blood vessels. Let your doctor know ahead of time if you're uncomfortable being confined in a small space because the test is conducted in a tube-shaped machine.

Positron emission tomography (PET). Using an intravenous tracer solution that contains a tiny amount of radioactive material, a PET scan can produce detailed images of your blood vessels and highlight areas of inflammation.

Treatment for giant cell arteritis consists of high doses of a corticosteroid drug such as prednisone. Because immediate treatment is necessary to prevent vision loss, your doctor is likely to start medication even before confirming the diagnosis with a biopsy.

You'll likely begin to feel better within just a few days of beginning treatment. Unless you have complete vision loss, your visual symptoms will likely clear up within three months.

You may need to continue taking medication for one to two years or longer. After the first month, your doctor may gradually begin to lower the dosage until you reach the lowest dose of corticosteroids needed to control inflammation.

Some symptoms, particularly headache, may return during this tapering period. This is also the point at which many people also develop symptoms of polymyalgia rheumatica. Such flares can usually be treated with slight increases in the corticosteroid dose. Your doctor may also suggest a drug called methotrexate, which may help reduce the side effects of corticosteroids.

Corticosteroids can lead to a number of serious side effects, such as osteoporosis, high blood pressure and muscle weakness. To counter these potential side effects, your doctor is likely to monitor your bone density and may prescribe calcium and vitamin D supplements or other medications to help prevent bone loss. Your doctor is also likely to monitor your blood pressure and may recommend an exercise program, diet changes and medication to keep blood pressure within a normal range. Most side effects go away when the corticosteroid treatment is tapered and stopped.

When giant cell arteritis is diagnosed and treated early, the prognosis is usually excellent. Your symptoms will likely improve quickly after beginning corticosteroid treatment, and your vision isn't likely to be affected. Your greatest challenge in this case may be coping with any side effects of your medication. The following suggestions may help:

Eat a healthy diet. Eating well can help prevent potential problems, such as thinning bones, high blood pressure and diabetes. Emphasize fresh fruits and vegetables, whole grains, and lean meats and fish, while limiting salt, sugar and alcohol. Be sure to get adequate amounts of calcium and vitamin D. Experts recommend 1,200 milligrams of calcium and 800 international units (IU) of vitamin D a day for women over 50 and men over 70. Check with your doctor to see what dose is right for you.

Exercise regularly. Regular aerobic exercise, such as walking, can help prevent bone loss, high blood pressure and diabetes. It also benefits your heart and lungs. In addition, many people find that exercise improves their mood and overall sense of well-being. If you're not used to exercising, start out slowly and build up gradually. Your doctor can help you plan an exercise program that's right for you.

Get regular checkups. See your doctor to check for side effects of treatment and development of any complications.

Ask about aspirin. Ask your doctor about taking between 75 and 150 milligrams of aspirin daily. Taken daily, low-dose aspirin may reduce the risk of blindness and stroke.

Learning everything you can about giant cell arteritis and its treatment can help you feel more in control of your condition. Your health care team can answer your questions, and online support groups may also be of help. Know the possible side effects of any medication you take, and report any changes in your health to your doctor.

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